The occurrence of cancer in Poolesville will continue to be monitored after the U.S. Centers for Disease Control and Prevention did not find evidence of a cancer cluster in the rural town.

The Montgomery County Department of Health and Human Services, along with the Maryland Department of Health and Mental Hygiene, initiated a cancer cluster study in December after a resident contacted them with concerns. The initial analysis of data from the Maryland Cancer Registry did not uncover any unusual patterns, but more residents contacted the county and that "raised questions." The CDC was asked to assist with the study.

County health officer Dr. Ulder Tillman said residents who called discussed cancers "with some environmental links" but would not comment further, citing patient confidentiality. They determined there was not a problem after learning more about the specific cases and about the prevalence of cancer in town, she said.

Tillman said this was the first time in her six-year tenure with the department that the CDC has been involved in a county cancer study.

The CDC reported 10 days ago that it did not find any evidence of a cancer cluster, Tillman said at a Poolesville commissioners meeting Monday. The report is being vetted by county attorneys to ensure compliance with patient confidentiality requirements before it can be released, Tillman said.

"There was nothing that jumped out at us and said there are cancers here that make [Poolesville] look unusual in terms of an environmental exposure or some other exposure that we should follow up on," said Dr. Clifford Mitchell, the state's director of environmental health coordination.

A county report examining environmental concerns raised by residents is expected to be completed this year. Some residents have said they are concerned about high levels of naturally occurring alpha radiation-emitting particles in the town's water, which has never been out of compliance with federal or state standards.

The cancer registry includes data through 2006, and some of the roughly 40 residents at the meeting said it appeared that cancers have become more frequent in the past few years.

"It seems like it's a little premature to be concluding this," said Robin McCollum, whose son James was diagnosed with the rare bone cancer osteosarcoma. "Six months and incomplete data do not seem to be enough."

Health officials cast a wide net to identify potential causes for concern, Mitchell said, adding "our goal is to find a problem." The county will periodically review cancer frequencies in Poolesville for anything unusual, Tillman said.

"Science is not perfect on this point and none of us would claim that," Mitchell said. "…This is the best answer we can give after a lot of investigation. This is not closure, this is not saying we're going away and not coming back. This is recognizing that we can't give a complete answer and it's incumbent on us to keep looking."